fix: add workaround for UV 0.10.5 stripping execute bits from Ray binaries

- Introduced an environment variable `UV_LINK_MODE` set to `copy` for the `ray-node` container in the skypilot-config.yaml to address issues with Ray binaries in UV 0.10.5.

Author: bradhilton

skypilot-config.yaml

@@ -400,3 +400,9 @@ config:
     pod_config:
       spec:
         schedulerName: gpu-binpack
+        # Work around uv 0.10.5 stripping execute bits from Ray binaries.
+        containers:
+          - name: ray-node
+            env:
+              - name: UV_LINK_MODE
+                value: copy